Techniques for specifying a reference point of an object for calculating the position and the moving speed of the object have been disclosed.
For example, a technique to detect two opposite end points of an object near a subject vehicle in the horizontal direction and use, as a reference point of the object, any one of the end points that is not behind another object has been disclosed. However, an end point of an object is inaccurately detected not only when the end point is behind another object but also when the material or the surface shape of the object or the positional relation thereof with a sensor is unfavorable for the detection. Therefore, when an end point of an object is inaccurately detected not because the end point is behind another object but because of another factor, a reference point of the object may be inaccurately detected. That is, conventionally, it has been difficult to highly accurately specify a reference point of an object.